1. Field of the Invention
The present invention relates to a resin composition, and in particular, to a resin composition useful in manufacturing a prepreg, a laminate and a printed circuit board, and the prepreg, the laminate and the printed circuit board formed by using the same.
2. Description of the Related Art
Due to low dielectric constant, low dielectric dissipation and good thermal stability, it is common practice to employ a resin composition with epoxy resin as the main component to manufacture a laminate of a printed circuit board. However, as electronic products become smaller through miniaturization and demands for functionality get expand, printed circuit boards need to accommodate a growing density of components and more demanding requirements for signal transmission and signal frequency. Consequently, more stringent standards need to be met in terms of dielectric property and thermal stability of a laminate used in a printed circuit board. For example, for a high-speed high-frequency circuit, a substrate is required to have good insulating property, for example, low dielectric dissipation and low dielectric constant. Generally speaking, the lower the dielectric dissipation (dissipation factor, Df) and the dielectric constant (dielectric constant, Dk) are, the better the property is. If a difference in Dk is as high as 0.1, it indicates that the difference is significant; similarly, if a difference in Df is as high as 0.001, it indicates that the difference is significant. Environmental concerns have given rise to a preference for halogen-free flame retardant. Therefore, there has been a demand for a substrate material having good heat resistance and dielectric property and satisfying increasingly stringent environmental requirements.
The dielectric property and thermal property of a substrate material are relevant to components of a resin composition for forming the substrate material and contents of the components. For example, U.S. Pat. No. 6,667,107 discloses a resin composition for forming a prepreg and a laminate, in which a copolymer of styrene and maleic anhydride and a thermosetting resin are cured to provide preferable low dielectric property, preferable heat resistance, preferable moisture resistance and preferable adhesion to a copper foil. U.S. Pat. No. 7,090,924 discloses a thermosetting resin material specifically useful in manufacturing a laminate with low dielectric constant and low dielectric dissipation, where the thermosetting resin material contains an elastomer selected from a styrene-butadiene-divinyl benzene (SBDVB) terpolymer, a maleinized polybutadiene styrene copolymer, and mixtures thereof, a polyester and a brominated flame retardant, in which the content of the polyester is 1 wt % to 15 wt %, based on the weight of the composition solids. U.S. Pat. No. 7,425,371 also discloses a thermosetting resin material specifically useful in manufacturing a laminate with low dielectric constant and low dielectric dissipation. One difference between U.S. Pat. No. 7,425,371 and U.S. Pat. No. 7,090,924 lies in that the content of the polyester used is 2 wt % to 8 wt %, and it is defined that the polyester does not contain styrene.
Some resin compositions are formulated merely to provide the formed material with low dielectric property without particularly targeting heat resistance; or merely to provide the formed material with good heat resistance, without particularly targeting the dielectric property. Therefore, there is still in need for a novel resin formulation that can provide a composite material with good heat resistance and dielectric property and satisfy increasingly stringent environmental requirements.